Selective receiving system



y 1932- 5. Y. WHITE SELECTIVE RECEIVING SYSTEM Filed Jan. 17, 1928 INVENTQR I ATTORNEY Patented July 19, 1932 uNir o 'mi EPATEN-T OFFICE SIDNEY awnrrn, or'ivnw YORK, N. 2., ASSIGNOR, BY teem ASSIGNMENTS, r RADIO CORPORATION or AMERICA, or NEW YORK, 1\T. Y., a conronnrrqn or DELAWARE SELECTIVE RECEIVING SYSTEM r.

Application filed January 17, 1928. Serial No. 247,297.

This invention. relates to radio, and lilre high frequency ,receivingsystems in which it is desired to sharply favor signaling currents ofone frequency. to the exclusion of currents of nearby frequencies. It relates in particular to selective discrimination before the commencement of theusual amplification of the signal bearing currents.

An object of the invention is to take advantage in a novel: way of the discriminative characteristics of a-so-called rejector circuit. A further object is to employ components of the undesired currents to self-neutralize their effects on the receiving apparatus.

Further and more definite advantages will appear-from the following specification and drawing, in which the single figure represents a preferred embodiment of the invention.

Referring now more particularly to the drawing, the vacuum tube or other. amplifying device 1 is energized by the input circuit 2 composed of the customary inductance 3 and capacity 4, either one or both of which may be variable, though the circuit need not necessarily be tuned, in which case condenser 4 can well be omitted. Other parts of the amplifying circuit are of customary arrangement having terminals 5 for a B-battery and output terminals 6. The coil 3 may be coupled to two or more'coupling coils 8 and 9, which are arranged to produce magnetic flux in reverse directions. These coils have a common connection 10 to ground 11 and any current which flows through them to this ground connection will produce opposite effects upon the coil 3 so that with like amounts of current, equal inductance and coupling no efiect will be caused upon the coil 3. These two coils- 8 and 9 are arranged in two'substantially similar coupling circuits l4 and 15, each of which consists of an additional inductance and a wire of considerable length which is intertwine'd with another wire in'the other cir cuit. Thus the circuit 14 consists of the coupling coil 9, the impedance 16 and the wire 17 which is intertwined with the wire 18 of the circuit 15. The circuit consists of a coupling coil 8, the impedance 19 and the intertwined wire 18. 5 r

. Theterminals of the wires 17 and 18, as in- I dicated at 20, may be separated or connected by any suitable impedance such as a condenser, resis'tance or other device. In this way, it. can be seen that the two circuits are substantially similar. .With such an arrangement and with equalcoupling between the coils 3 and 8, and 3 and 9, substantially no effect will be produced in the input circuit of the vacuum tube by flow in them of substantially equal currents tothe ground connection 10. .It is also apparent that any signal waves impinging upon the intertwined wires 17 and 18 will produce like efi'ects upon the circuits connected thereto, particularly because of the close inductive and capacitive relations of these wires. of the ordinary twisted lamp cord or a similar construction. It is not intended to be limited to the use of two wires, but a plurality might .well be used each having a separate coupling coil similar to 8 and 9 and so arranged as to balance out the effects of common currents in the grounded connection. I

However in the arrangement shown only two such circuits are used, to one of which is coupled the rejector circuit 22 consisting of the inductance 23 and variable capacity 24. By adjusting the capacity, the circuit 22 may be selectively limited to currents of a particular frequency in effecting the coil 8 coupled to the input coil 3 of the amplifier. Inasmuch as the other circuit 14 is substantially unaffected-by the ,rejector circuit 22, currents of this reduced or absorbed frequency are permitted to flow therein andwill affect the coil 9 coupled to the coil 3. All other frequencies will remain in substantially the same relation to each other which they previously as sumed thereby causing little or no effect upon the input coil 3.

In constructing the rejector it is preferable to have the winding 19 of few turnscompared to the number of turns in winding 23, but with a close physical and therefore electrical relation to each other. It is also desirable to form the turns of winding 19 of large wire to maintain as low resistance as possi ble to undesired: frequencies; shouldbeso chosen that itofiers as near as These wires may take the form" Winding 16 i possible the same impedance to undesired frequencies as does the winding 19 including its, mutual relation to the rejector, thus balancing the two circuit legs. The importance of balance also makes the twisted form of antenna preferable, assuring as it does that both sides of the circuits are alike.

If the condenser 4 is adjusted so as to tune the input circuit 2 to the same frequency as the rejector circuit 22, a still sharper differentiation of the accepted frequency will result. Thus it is possible to obtain amuch higher order of selectivity and overcome stronger interfernce ofnear-by frequncies than would otherwise be possible.

The intertwined wires 17 and 18 may well be arranged in the form of the ordinary antenna, or theymay be connected or coupled with any device in which a large number of frequencies are present, one or more of. which is desired to be separated out or amplified. 1V here a plurality of frequencies are to be selected, more than. one rejector circuit 22 may be used, preferably coupled to another of the circuits 14: or 15., For instance, if another rejector circuit were used in the arrangement shown, this would be coupled directly to the impedance 16 and tuned to the second frequency.

It is thus seen that the undesired currents are handled in two components, so that only the difference if any between the two com ponents of any one frequency current can be effective in creating interference. In all 5-5 cases the difference is naturally substantially less than the whole, and by providing the twisted antenna and the otherwise carefuly balanced two circuit branches, I maintain the difference if any extremely low. Also, a properly constructed rejector as outlined will have a very sharply defined peak of high impedance for the selected current, so that at only the desired frequency is there a substantial unbalance or difference to send through a signal.

It is not intended to be limited to the exact methods and arrangements shown but any variations therefrom and modifications are intended to be covered hereby within the scope of the appended claims.-

I claim:

1. In a high frequency receiving system, a multiple part antenna, a pair of branch circuits in extension thereof, like impedance means having like effective inductance in each of said branch circuits for equalizing the impedance of'said circuits, a coupled rejector for unbalancing said circuits at a selected frequency, and a circuit equally but oppositely coupled to said branch circuits.

2. In a high frequency receiving system, amultiple part antenna, branch circuits connected with each part, like-impedancemeans having like effective inductance in each of said branch circuits for equalizingthe impedances of said circuits, a coupled rejector circuit for unbalancing said circuits at a selected frequency, and a circuit equally but oppositely coupled to said branch circuits.

3. In a high frequency receiving system, an antenna comprising a pair of wires twisted in non-conductive, relation to each. other, branch circuits connected to each of said wires, like impedance means in each of said branch circuits for equa-lizingthe impedances thereof, the eflective inductance of each of said impedance means being substantially equal, a coupled rejector circuit for unbalancingsaid circuits at a selected frequency, and a circuit equally but oppositely coupled to'said branch circuits.

Y i. In a high: frequency receiving system, a plurality of antennae, circuits in extension of each of said antennae, impedance means for. equalizing the impedances of said cin cuits, the effective inductance: of: each of said:

impedance means being: substantially equal, a tunable rejector circuit coupled to. one of: said circuits forunbalancing said circuits at arselected-frequency, and a. tunable circuit equally but oppositely coupled; to each of said circuits.

5.. In. a..highfrequency. receiving" system,

an antenna comprisingapair of wires twisted together and insulated from. each. other, branch CHCUItS connected to each. of said wires, impedance means. in each of: said.

branch circuitsincludingan. adjustable rejector circuit coupled to one branch, the; effective: inductance of each, of Said? branch circuits being. substantially. equal; and. a; circuit; oppositely coupled to. said. branch. circuits.

6.,In a high frequency: receiving system, an antenna comprising a pair of wires tw-istedi together and insulated from each; other, branch circuits, connected to each of: said wires, and inductivemeans in each. ,ofsaid;

circuits for balancing the effective. induce tance; of each;of said branch circuits including adjustable-,means for electrically unbal. ancingsaid circuits at aselected frequency.

7 In a high frequency receiving, system the combination. of a. plurality of antenna,-

circuits in extension of. said antennaaeachof said ClI'CllltS- containing; a plurality of, inductances forming pairs of. inductances, av

ground connection to a point symmetrically disposed with reference to said pairs, at res:

onant circuit equally andoppositely-coupled to-one pair of said inductances, a rejector circuit coupled to one of another pair of inductances, the effective inductance of said inductance Withthe rejector circuit coupled. thereto being substantially equal to the. in-- ductance of the other inductance of said last mentioned pair.

8. In a high frequency. receiving system, the combination of aplurality of antennae, in close proximity to each other. but-conductively separated, circuits in extension of said antennae,each of said circuits containing a plurality of coils arranged in pairs with respect to said circuits, a grounded connection symmetrically disposed between said circuits, a resonant circuit equally and oppositely coupled to one pair of said coils, a

7 rejector circuit coupled to one of another pair of said coils, the efi'ective inductance of said coil with the rejector circuit coupled thereto being substantially equal to the inductance of the other coil of said last mentioned pair of coils.

9. In a high frequency receiving system, the combination of a plurality of antennae twisted together in non-conductive relation to each other, a grounded circuit in extension of eachvof said antennae, said grounded circuits being similar and each containing a plurality of-coils forming sets, a resonant circuit equally and oppositely coupled to one set of said coils, a rejector circuit coupled to one of another set of said coils, the effective inductance of said coil with the rejector circuit coupled thereto being substantially equal to the inductance of the other coil of said last mentioned pair.

In testimony whereof I affix my signature.

SIDNEY Y. WHITE. 

